Operating principle and performance analysis of a novel flux–torque regulation hybrid excitation machine with axial–radial magnetic circuit using magnetic network

In order to solve the problem of the decreasing torque density caused by the complex structure of the hybrid excitation machine, a novel flux–torque regulation hybrid excitation machine with axial–radial magnetic circuit is proposed by the authors, which innovatively realises the increase of additional torque and the regulation of the magnetic field by an axial structure. In particular, the additional torque has a certain boost to the output torque under the flux‐weakening condition of the machine. Based on the equivalent magnetic network model, the flux regulation principle of the machine is analysed, and the expressions for the flux linkage and no‐load back electro‐motive force are given to obtain the important factors affecting the flux regulation. Based on the analysis of complex forces generated by the rotating permanent magnet in the coupling magnetic fields, the generation and control principle of the additional torque is expounded. The expression of the additional torque is derived by the Maxwell stress tensor method, which can determine the main influencing factors and these relationships. Finally, the rationality of the proposed hybrid excitation machine structure is verified by experiments. In this paper, a novel flux–torque regulation hybrid excitation machine with axial–radial magnetic circuit is proposed, which innovatively achieves the regulation of the magnetic field and the increase of the additional torque. The machine can have a large output torque under flux‐weakening condition because of the additional torque generation. The equivalent magnetic network models of the novel machine are built to obtain the expressions for the flux linkage and no‐load back EMF, and the results are compared with the finite element analysis results to verify the accuracy.